HR: 10:45h
AN: SP32A-02    [Abstracts]
TI: Determining the Sun's Deep Meridional Flow Speed Using Active Latitude Drift Rates Since 1874
AU: * Hathaway, D H
EM: david.hathaway@nasa.gov
AF: NASA/MFSC/NSSTC, Mail Code XD12, Huntsville, AL 35812 United States
AU: Wilson, R M
EM: robert.m.wilson@nasa.gov
AF: NASA/MFSC/NSSTC, Mail Code XD12, Huntsville, AL 35812 United States
AB: Dynamo models that incorporate a deep meridional return flow indicate that this flow regulates both the period and the amplitude of the sunspot cycle (Dikpati & Charbonneau 1999, ApJ, 518, 508 and Charbonneau & Dikpati 2000, ApJ, 543, 1027). We recently examined the equatorward drift of the active latitudes (as given by the centroid of the sunspot areas in each hemisphere) and found evidence supporting this view (Hathaway et al. 2003, ApJ, 589, 665 and Hathaway et al. 2004, ApJ, 602, 543). In those studies we fit the equatorward drift in each hemisphere for each sunspot cycle with a simple parabola - giving us a drift rate and its deceleration for each hemisphere/cycle. Here we analyze the same data (the Royal Greenwich Observatory/USAF/NOAA daily active region summaries) to determine the drift rates in each hemisphere on a yearly basis (rotation-by-rotation measurements smoothed to remove high frequencies) and fit them with a simple model for the meridional flow that provides the meridional flow speed as a function of latitude and time from 1874 to 2005. These flow speeds can be used to test dynamo models -- some of which have predictive capabilities.
DE: 2162 Solar cycle variations (7536)
DE: 7536 Solar activity cycle (2162)
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly